Canine endothelial dysfunction and Descemet’s stripping endothelial keratoplasty (DSEK)
Corneal endothelial dysfunction occurs in canine patients most commonly as a result of canine endothelial dystrophy and intraocular surgical procedures.
The endothelium is a single layer of cells that maintains the fluid content within the cornea. Endothelial cell population decreases with age and have limited regenerative capacity. The combination of these two factors can cause fluid accumulation within the stroma. As a result, the cornea loses its transparency and the individual may develop decreased vision. Corneal ulcers can ensue, causing ocular discomfort. Canine endothelial dystrophy represents a disease process similar to Fuchs dystrophy in humans.
In our canine patients, palliative therapy is most commonly employed for canine endothelial dystrophy. Current medical and surgical therapies are often employed to manage recurrent ulcers, however, these patients have limited visual potential. The only definitive treatment for this condition is a corneal transplant.
In humans with Fuch’s dystrophy, partial thickness corneal transplants to replace the diseased endothelial layer with a healthy population of cells are the mainstay of treatment for the last decade.
DSEK in dogs
Corneal transplant (full thickness/ partial thickness) is the only definitive treatment for long term vision in corneal endothelial dystrophy. This study was designed to regain long term vision in dogs with endothelial dystrophy, using a technique that is well-practised in the human field.
DSEK is a partial thickness corneal transplant that replaces the diseased endothelial layer with a healthy donor endothelium. During surgery, the abnormal endothelium is first removed. The endothelium was retrieved from a donor cornea and transplanted carefully into the diseased eye. The graft is held in place with an air bubble and the patient recuperates quietly at home. This is a novel approach in the field of veterinary ophthalmology. Eye Clinic for Animals were the first to develop this technique, starting with pre-clinical trials in 2017. Our first clinical trial finished in 2018. Since then we have been doing these DSEK surgeries as routine.
Our success rate with DSEK surgery in dogs is 84.6%. The patients that had graft failure had underlying chronic allergies. Therefore, we have since excluded patients with allergic conditions. Other complications that can happen are graft dislocations and delayed graft rejections. We have not encountered delayed graft rejections, like humans do. In our canine cases, we have also not encountered complete graft dislocations.
The potential recipients of corneal donors will be placed on a waiting list. The owners of the recipients will be called when a suitable donor with a healthy cornea is available. Surgery should ideally take place within the first 1-2 days for maximum success.